Vcsn 2.5 (January 28th, 2017)


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The Vcsners are proud to announce the release of Vcsn 2.5, aka the k-lightest release!

Noteworthy changes include:

  • two new implementations to compute the k-lightest paths (aka "best" paths: with the smallest weights) in tropical automata.
  • several new demos showing how to use the C++ library, including a translator from (French) text messages (aka SMS) into French.
  • better error messages with caret-style locations.
  • a new means for the users to configure Vcsn. This adds a new prerequisite to build Vcsn: libyaml-cpp.
  • a much better and faster caching system of runtime generated C++ code. Users of dyn (and therefore of Python) should note an improved amortization of the compilation costs.
  • several portability issues reported by users were fixed.

For more information, please, the NEWS file.

People who worked on this release:

  • Akim Demaille
  • Clément Démoulins
  • Clément Gillard
  • Sarasvati Moutoucomarapoulé
  • Sébastien Piat
  • Younes Khoudli


Available Ports

  • Docker
Run this command to pull and start the Vcsn docker image on port 8888
docker run -d -p 8888:8888 lrde/vcsn:2.5
  • Debian Jessie
Run this command
echo 'deb stable/' >/etc/apt/sources.list.d/lrde.list
apt-get update
apt-get install vcsn
# Jupyter is not currently available on Debian
apt-get install python3-pip python3-dev libzmq3-dev
pip3 install jupyter
  • Archlinux (AUR)
Run this command:
yaourt -S vcsn
  • MacPorts
Run this command:
sudo port sync && sudo port install vcsn


  • Tarballs (sources to compile):


In order to compile Vcsn 2.5, you need:

Boost (version 1.49 or later) provides free peer-reviewed portable C++ source libraries (at least the Boost.Python and Boost.Regex components, and probably others).
Compiler cache.
C++ compiler
Clang 3.6 or newer and GNU G++ 4.9 or newer are known to work properly.
To build the C++ reference manual.
The display of automata is made using AT&T Graphviz library. (On Ubuntu/Debian, install the following package: graphviz)
The Flex scanner generater, 2.5.37 or better.
Although not strictly needed, it is required if you want to enjoy the Vcsn interactive notebooks.
Python 3 is required
Version 0.5.1 or 0.5.3 or more recent, but not 0.5.2.